2010 Soybean & Wheat Weed Update. Dallas Peterson Department of Agronomy K-State Research & Extension

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1 2010 Soybean & Wheat Weed Update Dallas Peterson Department of Agronomy K-State Research & Extension

2 Current Weed Control Issues Crop Price/Herbicide Cost fluctuations New Herbicide Technologies New Trait Technologies Herbicide Resistance

3 New Herbicides and Technologies for Soybeans Sharpen OpTill Liberty Link Soybeans

4 Kixor New active ingredient (Saflufenacil) from BASF. Foliar and residual herbicide activity. PPO mode of action. Component of several herbicides: Sharpen Kixor alone Integrity Kixor plus Outlook Optill Kixor plus Pursuit

5 Sharpen Contains 2.85 lb saflufenacil (Kixor) per gallon. Labeled as a preplant or preemergence treatment in corn, sorghum, soybeans, wheat, and cotton. Can be used as a preharvest aid in sunflowers. Good burndown activity on various broadleaf weeds including marestail, pigweeds, kochia, ragweeds, velvetleaf and others. Residual weed control dependent on application rate. ~ 7-10 days residual control per oz of Sharpen. Rates and timings vary by crop.

6 Sharpen in Soybeans Timing: EPP to preemergence Rates: 1 oz/a primarily for burndown activity. Adjuvants: MSO or COC + AMS or UAN must be used for foliar activity. May be especially useful to help control glyphosate resistant marestail as part of burndown treatment with no waiting interval before planting soybeans. May want to use OpTill instead of Sharpen for enhanced residual weed control.

7 OpTill Contains 17.8% saflufenacil (Kixor) plus 50% imazethapyr (Pursuit) WDG. Timing: EPP through preemergence. Application rate: 2 oz per acre = 1 oz Sharpen and 4 oz Pursuit Adjuvants: MSO or COC plus AMS or UAN Limited residual activity from Kixor component May be especially useful to help control glyphosate resistant marestail as part of burndown treatment with some early season residual control, especially from the Pursuit component.

8 Sharpen & OpTill Restrictions Must allow 30 day preplant interval if applied to coarse textured soils with less than 2% organic matter. Do not apply after soybean have reached the cracking stage or after emergence or severe injury will occur. Do not graze or feed harvested forage, hay, or straw to livestock following 0pTill application, or before 65 days after application of Sharpen. Do not apply within 30 days where other PPO inhibiting herbicides such as Valor or Authority are applied to soybeans. Do not tank-mix OpTill with clomazone containing herbicides.

9 Liberty Link Soybeans Liberty Link soybeans introduced in 2009 and more widely available for Allows the use of Ignite (new formulation of Liberty) on LL soybeans. Timing is critical for good weed control. Best approaches include sequential programs with a preemergence program followed by Ignite or a two-pass Ignite program.

10 Ignite New formulations of glufosinate (Liberty) containing 2.34 lb ai/gal. Rate: 22 to 36 oz/a. Single application at oz/a. Sequential applications at 22 oz/a. Total maximum per season = 44 oz/a. Timing: Emergence to bloom stage of soybean growth. Adjuvant: AMS at 3 lb/a. Application timing, spray coverage, temperature, humidity, light intensity, and time of day all critical to performance.

11 Sk Weed control and soybean yields in Liberty Link soybeans, Manhattan, KS, 2009 (SB200911). Application RR SB Herbicide Rate Timing Lacg Paam Vele Ilmg Sorg Corn Yield (oz/a) (% control) (Bu/a) Ignite 22 P Ignite/Ignite 22/22 EP/Seq Valor/Ignite 2/22 PRE/P Auth Assist/Ignite 8/22 PRE/P Prefix/Ignite/Ignite 3/22/22 PRE/P Untreated 33 LSD (5%) Lacg = large crabgrass; Paam = Palmer amaranth; Vele = velvetleaf; Ilmg = ivyleaf morningglory; Sorg = sorghum; RR corn = volunteer Roundup Ready corn.

12 Untreated

13 Ignite

14 Valor/Ignite

15 Sk Weed control and soybean yields in Liberty Link soybeans, Manhattan, KS, 2008 (SB200817). Application RR SB Herbicide Rate Timing Lacg Paam Vele Ilmg Corn Yield (oz/a) (% control) (Bu/A) Ignite 22 P Ignite/Ignite 22/22 P/Seq Valor/Ignite 2/22 PRE/P Auth First/Ignite 3.2/22 PRE/P Prefix/Ignite/Ignite 3/22 PRE/P LSD (5%) Lacg = large crabgrass; Paam = Palmer amaranth; Vele = velvetleaf; Ilmg = ivyleaf morningglory; Sorg = sorghum; RR corn = volunteer Roundup Ready corn. P treatments applied 22 days after soybean emergence = Too Late.

16 Future Technologies in Soybeans Crops stacked with multiple herbicide resistant traits. Optimum GAT soybeans from DuPont 2011? ALS and Glyphosate resistance Different event than RR soybeans Metabolism based resistance Legal issues with Monsanto Dicamba resistant soybeans from Monsanto 2013? DHT resistant soybeans from Dow AgroSciences 2013? Resistance to 2,4-D Metabolism based resistance

17 Dicamba Resistant Soybeans 48 oz/a Clarity, 1 WAT

18 Glyphosate Resistance Evaluations at KSU Common waterhemp Marestail Giant ragweed and common ragweed Kochia Palmer amaranth

19 Glyphosate Resistant Kochia? Poor control of a wandering row of kochia with glyphosate was observed in a field of Roundup Ready cotton in Stevens county, KS in the summer of Kochia seed was collected from the uncontrolled plants in the cotton field in Stevens county and from an uncropped area in Finney county in the fall of Greenhouse experiments were conducted to compare the efficacy of glyphosate at various rates on the two kochia populations.

20 Materials and Methods S and R biotypes of kochia were grown in the greenhouse and treated when plants were 1 to 2 inches tall. Kochia plants were treated with Roundup Weather Max at 0.38, 0.75, 1.5, and 3 lb ae/a (11,22, 44, & 88 oz/a). Weed control was visually evaluated 2 and 4 weeks after treatment.

21 Kochia biotype response to glyphosate, 4 WAT. Herbicide Rate ae Product (lb/a) (oz/a) Biotype Finney Stevens (% control) Roundup WMax + AMS LSD (5%) 9

22 Kochia biotype response to glyphosate, 4 WAT. Herbicide Rate ae Product (lb/a) (oz/a) Biotype Finney Stevens (% Mortality) Roundup WMax + AMS LSD (5%) 13

23 Glyphosate Resistant Kochia? (2 WAT) Stevens Co. Finney Co. Roundup WMax: Untreated 0.38 lb (11 oz) 0.75 lb (22 oz) 1.5 lb (44 oz) 2.25 lb (66 oz) 3 lb (88 oz)

24 Summary A biotype of kochia in southwestern Kansas has developed a low level of resistance to glyphosate. Exclusive use of glyphosate, especially at reduced rates may result in increased tolerance by weeds. Producers should use labeled rates, tank-mix and/or rotate herbicides with different modes of action to manage and minimize the risk of further development of glyphosate resistant weeds.

25 Marestail Escapes from Glyphosate

26 Glyphosate Resistant Marestail Assay Sumner Co. Miami Co. Check Glyphosate Rate: 1 pt 1 qt 1.5 qt 0

27 Glyphosate Resistant Marestail Assay Sumner Co. Miami Co. Check Glyphosate Rate: 1 pt 1 qt 1.5 qt 0

28 Managing Marestail Timing, Timing, Timing! Atrazine + 2,4-D in corn or sorghum Utilize 2,4-D, dicamba, Sharpen and/or residual herbicides in fall and early spring burndown in no-till. Control marestail in the wheat crop. Don t skimp on rate or appropriate spray additives. Use appropriate treatments.

29 Postemergence marestail control in soybeans at Manhattan in 2009 (Peterson & Thompson). Treatment Rate 1WAT 5 WAT 10 WAT (% Marestail control) Roundup PMax 22 oz Roundup PMax 44 oz Cadet 0.9 oz RU PMax + Cadet oz FirstRate 0.3 oz RU PMax + FirstRate oz Classic 0.5 oz RU PMax + Classic oz Raptor 4 oz RU PMax + Raptor 22+4 oz LSD (5%)

30 Marestail Control in Soybeans Roundup PM 22 oz/a Cadet Roundup PM + Cadet Roundup PM + FirstRate

31 New Herbicides for Wheat PowerFlex Huskie Pulsar

32 PowerFlex New herbicide (pyroxsulam) from Dow AgroSciences for postemergence control of cheatgrass, Italian ryegrass, and broadleaf weeds in wheat. Rate: 3.5 oz/a Adds: NIS Timing: Spring or fall postemergence from 3 leaf to jointing stage of wheat. Weeds: ryegrass, and many broadleaf weeds. Minimal Crop Rotation Restrictions Cheat, Japanese brome, downy brome (F), Italian 9 Months for most crops. May be shortened for some crops. ALS inhibiting herbicide similar to Olympus.

33 Weed control and wheat response to herbicide application timing at Manhattan, KS in 2009 (WH200901). Wheat Herbicide Timing Vig Red Yield Hebi Blmu Dobr Cheat (%) (Bu/a) (% control) PowerFlex Fall Olympus Beyond PowerFlex Winter Olympus Beyond PowerFlex Spring Olympus Beyond Untreated 48 LSD (5%) Fall = 11/26/08; Winter = 1/21/09; Spring = 3/17/09; Hebi = henbit; Blmu = blue mustard; Dobr = downy brome.

34 ALS Resistant Cheatgrass? Several cases of poor cheatgrass control with Olympus and Maverick herbicides were reported in Japanese brome seed was collected in Cowley county and cheat seed was collected in Dickinson county from fields that had control problems and extensive histories of ALS herbicide use. Greenhouse experiments were conducted to confirm the occurrence of ALS resistance and to evaluate cross resistance among ALS herbicides.

35 Bromus biotype responses to ALS herbicides at WAT 4 Japanese Brome Cheat Population Population Herbicide Rate Susc. Res. Susc. Res. (oz/a) (% control) Olympus Olympus Maverick Beyond PowerFlex LSD (5%) 6

36 Cheat Response to ALS Herbicides, 2WAT R - Cheat S - Cheat Olympus 0.9 oz Olympus 9 oz Maverick 0.67 oz Beyond 4 oz PowerFlex 3.5 oz Check

37 ALS Resistant Cheatgrass ALS resistant cheat and Japanese brome populations are present in Kansas. Cross resistance occurs among all ALS herbicides evaluated, but to a lesser degree with Beyond than to Olympus or Maverick. Producers will have to rely on cultural practices to manage cheatgrass problems in fields where ALS resistance has developed.

38 R Bushy Wallflower Biotype Response to ALS Herbicides Express Maverick Olympus Beyond Check S R S Glean: 10X 100X Ally Amber

39 ALS Susceptible and Resistant Flixweed Response to ALS Herbicides, 5 WAT. Resistant Susceptible Glean Express Power Flex Olympus Untreated

40 Summary Populations of ALS resistant bushy wallflower and flixweed have developed in central Kansas. Alternative control measures such as 2,4-D, MCPA, or Huskie will need to be utilized to achieve acceptable control of ALS resistant mustard weeds.

41 Huskie New herbicide from Bayer which is a premix of pyrasulfotole and bromoxynil for postemerence control of broadleaf weeds. Rates: 11 to 15 oz/a Adds: NIS + N source Timing: Spring or fall postemergence from 1 leaf to flag leaf emergence when weeds and crop are actively growing. Weeds: Mustards, pennycress, henbit, kochia, Russian thistle, wild buckwheat*, prickly lettuce. Minimal Crop Rotation Restrictions 4 Months for sorghum and soybeans 9 months for most other crops Cost: 11 oz of Huskie ~ $8.50

42 Huskie Safe treatment for fall and spring application for general broadleaf weed control. Control of ALS resistant weeds, including: Kochia Russian thistle Bushy wallflower Flixweed/Tansy mustard

43 Pulsar New premix from Syngenta which contains 0.73 lb dicamba (Banvel) and 0.95 lb fluroxypr (Starane) per gal. for broadleaf weed control in wheat. Rates: 8.3 to 12.5 oz/a Adds: NIS optional with dry conditions Timing: Spring or fall postemergence from 1 leaf to flag leaf emergence when weeds and crop are actively growing. Weeds: kochia, Russian thistle, and wild buckwheat Weak on mustards Tank-mix with MCPA for broader spectrum control

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45 Sharpen Preharvest Aid in Sunflowers Timing: After sunflower are physiologically mature Seed moisture < 36% At least 7 days prior to harvest Rate: 1 to 2 oz/a Adjuvant: MSO at 1% v/v Do not treat sunflower grown for seed production

46 Sharpen at 2 oz/a 4DAT

47 Dallas Peterson Extension Weed Specialist